1. Field of the Invention
The disclosure relates to machined objects, and particularly to a system and method for controlling movement of an object on a machine.
2. Description of Related Art
Linear movement of an object is often required in both testing and manufacturing process. Usually, a working point of an object is moved from an initial position to a target position along a linear track as depicted in FIG. 3. The object may be moved by a roller-type guideway, ball screws, or other means. Position of the working point may be determined by an optical sensor, and speed of the linear movement determined by comparing distance travelled with travel time. The speed of the linear movement may further be determined dynamically by a processor and controlled by a driver servo.
FIG. 3 is a schematic diagram of a method for controlling movement of an object on a machine. The object X is movable along a track on the machine. As shown, point A is an initial position of the object X on the track, and point D is a target position for the object X. A point C is a current position of the object X when the object X is moving on the machine. A point B is an exemplary point at which the object X starts decreasing speed. A point W is a working point on the object moving on the machine, usually the point of the object X closest to the point D. A speed V is a current speed of the object X, varying during movement of object X on the machine. A buffer distance parameter P is used for establishing point B, and also determining where the object X will start decreasing speed V. Additionally, L is a distance between the point C and the point D.
The object may, however, experience displacement during movement from the initial position to the target position, when speed is not decreased sufficiently or in a timely manner, resulting in the object passing the target position due to inertia. In some cases, displacement may not be a problem since the object may be returned to the target position. However, in other cases, particularly in precision machinery, displacement results in a severe problem, impacting accuracy and timing-based efficiency of production. Moreover, if the working point is within a proximity or a limited range of the target position, the displacement may cause object collision, machine damage, and affect process due to over-damping by the machine.
What is needed, therefore, is a system and method for controlling object movement on a machine.